1. Field of the Invention
The present invention relates to an airbag device having an inner pressure adjusting unit that can adjust an inner pressure of an airbag thereof.
2. Description of Related Art
Conventionally, a vehicle such as automobile is provided with an airbag device to protect a passenger(s) from an impact in a vehicle collision.
With regard to the airbag device, various types are provided such as one for protecting a passenger seating on a rear seat and one for protecting a passenger from an impact in a side collision or a roll-over in addition to one for protecting a passenger seating on a driver's seat or a front passenger's seat. Although an airbag shape or the like may be varied according to an installed position, most of airbags have a configuration for inflating and developing a bag-like airbag by high-pressure gas generated by an inflator at a vehicle collision to protect a passenger(s) from a collision impact by absorbing the collision impact by the airbag.
Since the conventional airbag device inflates the airbag in a blink by the high-pressure gas generated by the inflator and then develops the airbag in a prescribed direction, the airbag may contact with a passenger seating near the airbag device or the like at a development early stage.
Therefore, an airbag device for a vehicle had been proposed, which can reduce an impact by adjusting an inflating pressure of its airbag by preliminarily detecting a state where a passenger or the like is seating near the airbag device at a development early stage or by generating high-pressure gas by one inflator at a development early stage and then by other inflators to develop an airbag into a prescribed shape.
Another airbag device had been proposed, which restricts an inner pressure elevation at an inflation early stage and then raise the inner pressure up to a sufficient high-pressure after a passenger being restrained by its airbag (e.g. Patent Document 1: Japanese Patent Application Laid-Open No. 2005-14863).
In the airbag device, an adjusting means is provided near vent holes of its airbag, which allows a gas ejection from the vent holes at a development early stage of the airbag.
The vent holes are closed by the adjusting means according to a deploying condition of the airbag to cut off gas ejection from the vent holes after transition from the development early stage to a development subsequent stage.
Since some of gas within the airbag is ejected from the vent holes at the development early stage of the airbag, an impact at the development early stage can be reduced.
Since the vent holes are closed by the adjusting means according to a deploying condition of the airbag after the transition from the development early stage to the development subsequent stage and then an inner pressure of the airbag rises quickly, the passenger can be restrained firmly due to an inner pressure of the airbag that has risen sufficiently when the passenger has been restrained by the airbag.